Toothbrush



E. M. MCNALLY Feb. 6, 1934.

TOOTHBRUSH Filed April 28, 1931 nvex/:JYQV

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Patented Feb. 6, 1934 PATENT OFFICE TOOTHBRUSH Edwin M. McNally, Indianapolis, Ind., assigner to The Tefra. Co., Indianapolis, Ind., a corporation of Delaware Application April 28, 1931. Serial No. 533,473

2 Claims.

My invention relates to toothbrushes and particularly to that class of toothbrushes in which a tufted brush head is removably held in operative position in a handle member by means of a 5 loop formed on the handle, into which loop the brush head is forced serving to tension the loop so as to hold the head by an effective frictional grip. As is well understood in the toothbrush art, it is an essential feature of an acceptable toothbrush for the market that the part of the frame-work of the brush which comes into contact With the teeth, gums, and lips of the user shall be of comparatively soft material, preferably a non-conductor of heat and electricity, thus "precluding the use of metal for the handle or at least for the outer surface of the loop portion of the handle.

For meeting the requirements of the trade for a toothbrush of this type, a construction has been Worked out such as that shown by Booty Patent No. 1,592,292 of July 13, 1926, in which the loop portion of the handle is formed of pyralin, or similar comparatively soft material, provision being made for a limited expansion of the loop to accommodate slight variations in the size and shape of the different brush heads which would :normally be used in turn with a single handle as the brush heads Wear out in continued use.

In brushes of this type `heretofore in use, the brush head also has been made of pyralin, rubber, or other soft moldable material, and such construction has been found very satisfactory from the standpoint of its initial efliciency. It has been found diflicult or impossible, however, on a commercial scale and at a reasonable cost, to make brush heads of such soft materials as those named or of any other comparatively soft material available for such uses without having an appreciable variation in the size or shape of such heads. It has been found in the use of some of the soft materials which would otherwise be acceptable that they do not stand up satisfactorily when subjected to the heat incident to sterilization or even to continued and often repeated immersions in hot water. It has been found with respect to other soft materials otherwise acceptable for this purpose that they are subject to the serious objection 'that they swell more or less in the course of weeks or months of use, particularly when used again and again in hot water. When a slightly over-size brush head of this type has been forced into the loop of the type shown in said Booty patent and has then expanded in long continued use so as to be of still 4greater size, there is a very grave danger that the loop itself will have been stretched and permanently distorted to such an extent as to render the loop no longer capable of gripping a normal sized brush head so as to hold it by friction as firmly as is desired in position in the loop.

It is the object of my invention to provide a form and arrangement of parts by which these difficulties shall be overcome so as to enable a handle and loop to be used continuously for a very long period with a series of different brush heads in succession without danger under normal circumstances of the loop becoming stretched or otherwise distorted so as to be loosened upon a normal sized brush head. To this end, it is one of my objects to provide a form of brush head which can be produced in large quantities upon a. commercial basis with a Very` great uniformity of size, and to provide such brush head of a material which will not swell or otherwise change its shape or size in long continued use. Ity is one of the objects of my invention to provide a brush` head of this character in combination with an arrangement of loop which shall effectively protect the brush head against contact with the teeth or tissues of the mouth during use of the brush.

It is another object of my invention to irnprove devices of this type in sundry details hereinafter pointed out. The preferred means by which I have accomplished my several objects are illustrated in the drawing and are hereinafter specically described. That which I believe to be new and desire Vto cover by Letters Patent is set forth in the claims. y

In the drawing,-

Fig. 1 is a side View of brush; 1 l

Fig. 2 is a face view of my preferred form of block comprising the head in which the tufts of bristles are mounted;

Fig. 3 is a vertical section taken on line 3-3 of Fig. 2;

Fig. 4 is a face View of the loop portion of the" handle member of my improved brush;

Fig. 5 is `a Vertical sectional View through a fragmentary portion of a brush Ahead showing an intermediate step of the operation of applying a tuft of bristles to my improved brush head; i

Fig. 6 is a view similar to Fig. 5 but showing a later phase of the operation of applying the bristles;

Fig. '7 is a View similar to Figs. 5 and 6 but showing the nal position of the Darts; and

Fig. 8 is a View similar to Fig. '7 but showing a slightly modified arrangement.

7 my improved form of Y Referring now to Figs. 1 to 7, which show an operative embodiment of my invention, 15 indicates a handle member provided with a loop 16 on one end thereof, the handle 15 and loop 16 be- 5 ing preferably formed integrally with each other.

In the form illustrated, the handle and loop are formed of a cellulosic material. As is best shown in Fig. 4, the loop 16 is provided with a flange 17 at one edge of the band forming the main portion of the loop, such flange serving as a stop for limiting the movement of the brush head into the loop. At the handle end of the loop, a longitudinally extending slot 18 is provided adapted to permit a limited spreading movement of the side portions of the loop against the stiffness strength of the handle portions at opposite sides of the slot.

In the preferred form of my improved brush, a brush head 19 is provided in the form of a block of aluminum alloy provided with a series of the sockets 20 opening at one face of the block, theinner ends of sockets 20 being rounded slightly as is clearly shown in Fig. 3. The block 19 is preferably covered on its outer surface with a thin nlm .3 of suitable insulating material, such lm being illustrated upon `an exaggerated scale in Fig. 3 and there indicated by the numeral 21. In the arrangement vshown this film is formed of aluminum hydroxide, but it may be formed of other com- :i` paratively soft insulation materials such as pyralin or Dyroxyline if desired.

. In the form of device as shown in my drawing, I have `secured the tufts 22 of bristles in position in the sockets 20 by means of staples 23. The ff staple 23 is first inserted into the socket 2O around the bristles 22, as shown in Fig. 5; the staple is then pressed downwardly serving to cause the legs of the stapleto move laterally by reason of the curvature of the inner end of the socket, as shown jin Fig. 6; upon further pressure on the staple 23, the staple is bent downwardly into tightly clamping positionupon the bristles and into tight frictional-engagement with the walls of the socket 20, serving to hold the bristles effectively in position .1 j in the socket.

In the form of device as shown in Fig. 8, the staple 24 is made of such material as to enable it under heavy pressure to pierce the wall of the socket 20y so as to hold the bristles in position not onlyk by a frictional grip but also by an anchoring effect. l

. By the use of aluminum for forming the brus head 19, Iv have been enabled to produce brush heads upon a commercial basis with a very vmarked uniformity in size and shape, being enabled readily to control the size and shape so as to provide the desired snug fit between the block and the loop 16 so as to yinsure that the brush head when rst forced into the loop 16 will provide the desired tensioning effect upon the loop. The uniformity of size of the brush heads is so great that as different brush heads of `this type are inserted in the loop 16 no appreciable difference can be noticed in the fit of the different blocks 19 in the loop. I have found in use that there .is no appreciable tendency for the metal block 19 in long continued use to cause any stretching of the loop 16. On the contrary, the loop 16 is maintained of so nearly its exact To Aoriginal size that after long continued use it is still capable of gripping a normal size brush head so as to hold it by friction satisfactorily in position in the loop.

By the provision of a lm of aluminum hydroxide upon the outer surface of the brush head 19, I have provided a lm which has more or less of an insulating effect. By reason of this layerof insulation, the metal head 19 is protected largely against contact with very hot or very cold water and is protected thus against extreme Vchanges of temperature except as the subjection to the heat or cold effect is prolonged. This is of considerable importance in connection with an aluminum brush head, since aluminum has a high specific heat value coupled with a very high conductivity, so that the aluminum head would unless insulated very soon absorb a comparatively large amount of heat from a stream of hot water so as to be kept uncomfortably hot for a very considerable time. This layer of insulation, in protecting the brush head from contact with a gold or silver lling in a tooth, also preventsthe voltaic action-which would other- Wise be likely to take place in the, presence of the slightly alkaline saliva in the mouth. The provision of the film also enables me to color the block 19 to advantage with a high degree of permanency. As is clearly shown in Fig. 1, the

loop 16 substantially completely covers the sides,

of the block 19 so as eifectually toprotect the block 19 against contact with the teeth, gums, or other tissues of the mouth of the user.

vWhile I prefer to employ the form of parts as shown in my drawing and as above described,

it will be understood that my invention is ot limited thereto except so far as defined by the scope of the claims.

I claim:-

1. In a toothbrush, the combination of a handle, a loop on one end of said handle and having an outer face portion at least formed of nonmetallic material, a brush head in the form of a block of metal adapted to be held in position.

so asto -be held rmly in position in the loop by frictional engagement therewith.

2. A toothbrush comprising in combination a handle, a loop formed of non-metallic material on one endof said handle,l and a brush `head `in the form of a block of aluminum alloy covered with a thin film of aluminum hydroxide and having a series of tufts of bristles secured in sockets opening into one face of said block, saidblock being of such size land shape as to be adapted to enter the loop and to be substantially completely covered at its sides by said loop when in position therein and as to ,place said loop under tension circumferentially thereof .so as to be held firmly in position in said loop by frictional engagemen therewith. f

. EDWIN M. MCNALLY. 

